Reaction of 2-Quinolyl Thiocyanate with C-Nucleophiles

• Published in: Chemical & pharmaceutical bulletin Vol. 40; no. 5; pp. 1090 - 1093
• Main Authors: IIJIMA, Chihoko, HIYOSHI, Emiko, MIYASHITA, Akira
• Format: Journal Article
• Language: English
• Published: Tokyo The Pharmaceutical Society of Japan 25.05.1992; 公益社団法人日本薬学会; Maruzen; Japan Science and Technology Agency
• Subjects: 2-iodoquinoline; 2-quinolyl thiocyanate; active methylene compound; carbanion; Chemistry; Exact sciences and technology; Heterocyclic compounds; Heterocyclic compounds with only one n hetero atom and condensed derivatives; ipso-substitution; Organic chemistry; Preparations and properties; sulfur attack; Active methylene compound; Nucleophilic reaction; Nitrogen heterocycle; Bicyclic compound; Ipso attack; Aromatic compound; Organic sulfide
• DOI: 10.1248/cpb.40.1090
• ISSN: 0009-2363

2-Quinolyl thiocyanate (2) was found to react with C-nucleophiles, i.e., phenylacetonitrile, p-chlorophenylacetonitrile, p-cyanophenylacetonitrile, p-methoxyphenylacetonitrile, ethyl cyanoacetate, and malononitrile, in two ways, depending on the nature of the reagent. The more reactive phenylacetonitrile carbanions attacked at the less reactive sulfur atom, which is less subject to steric effect compared with the 2-position carbon of 2, to give the corresponding sulfides (α-(2-quinolylthio)phenyl- (8), α-(2-quinolylthio)-4-chlorophenyl- (9), α-(2-quinolylthio)-4-cyanophenyl- (10), and α-(2-quinolylthio)-4-methoxyphenylacetonitrile (11)). The less reactive ethyl cyanoacetate and malononitrile carbanions attacked at the more reactive 2-position carbon of 2 to afford the corresponding ipso-substitution products (α-cyano-2-quinolineacetate (4) and 2-quinolinemalononitrile (7)). However, in the reaction of diethyl malonate carbanion, diethyl 2-quinolinemalonate (12) was not obtained, presumably for steric reasons.